For rapid clearance of routes through minefields the military have previously used primarily chain flails and mine ploughs. Theses are most appropriate for military purposes and have achieved far from the 100% clearance result that is desirable in civil mine clearance operations after a conflict is over. Civil mine clearing operations have thus been achieved by the time consuming and labor intensive method of using probes or, perhaps, mainly by the use of electromagnetic mine detectors. The latter are, in fact, very sensitive but there are AP mines that do not contain any metal at all and are thus not detected. Moreover, the number of false indications that have to be checked is always high, especially in areas where battles have occurred as there is always a multitude of fragments in the ground in such areas.
In latter years, however, increasing interest has been focused on mechanical mine clearance vehicles that operate in a similar way to the mechanical rotary cultivator principle. They have been shown to have good capacity, and although they cannot operate in all types of terrain they clearly constitute a positive addition to the field of mine clearing.
Many of these rotary cultivator type demining tools are designed with horizontal rotation shafts fitted with multi-disc cultivators, each disc usually being fitted with individual teeth around its periphery.
The basic concept for the rotary cultivator disc type of mine clearing device is described in WO 95/24604, while DE 4.442.135 describes a variant of the same basic concept in which the various discs incorporate very large teeth machined direct in the actual disc and with apertures to reduce the risk of damage in the event of mine detonations in or under the demining tool.
The objective with demining tools that function on the rotary cultivator principle is that they shall `chew` the mines in their path into small fragments or cause the mines to detonate. In practice it has been shown that usually mines are made to detonate in or under the demining tool which is usually no problem in the case of AP mines, but anti-vehicle and anti-tank mines easily cause damage to the demining tool. Consequently, it should be easy to repair or replace.
In practice, however, the main problem with demining tools of the above rotary cultivator type has not been damage to the demining tool by mine detonations initiated, but that individual mines--especially small AP mines--can pass undamaged through the demining tool. Quite simply, it has been difficult to achieve the virtual 100% mine clearance effect necessary in civil mine clearing. The cultivator discs cannot be located too densely as the closer they are to each other the higher the machine power that is needed.